Method and apparatus for cooling material in bulk



- March 31, 1959 K. J. SYLVEST 2,879,933

METHOD AND APPARATUS FOR COOLING MATERIAL IN BULK Filed June 5, 1957 I v5 Sheets-Sheet 1 v n NI:

ATTORNEYf March 31, 1959 K. J. S YLVEST METHOD AND APPARATUS FOR COOLINGMATERIAL IN BULK Fild June 5, 1957 3 Sheets-Sheet 2 March 31, 1959 K. J.SYLVEST METHOD AND APPARATUS FOR COOLING MATERIAL IN BULK 5 Sheets-Sheet5 Filed June 5, 1957 INVE O L ATTORNE s United States Patent CfiiiceMETHOD AND APPARATUS FOR COOLING MATERIAL IN BULK Karl Jens Sylvest,Copenhagen-Valby,

to F. L. Smidth & Co., of New Jersey Application June 5, 1957, SerialNo. 663,734 14 Claims. (Cl. 263-32) Denmark, assignor New York, N .Y., acorporation high temperatures and the heated air produced in the coolingoperation is utilized as secondary air in the kiln, in which thematerial was burned, and also, in some cases, as primary air formingpart of the combustible fuel-air mixture consumed in the kiln. Inaddition to the method, the invention includes a cooling apparatus, by

which the new method may be advantageously practiced; 30

In the cooling of very hot material, such as cement clinker, one methodused heretofore involves depositing the material in a layer on apermeable support and then passing cooling air through the support andlayer in a single pass. The support used in such an operation issubjected to very high temperatures where the material is depositedthereon and, as a result, it is necessary to make the support ofexpensive heat-resistent steel and, even then, the support has arelatively short life. In addition, cooling the material by passage ofair once therethrough is not highly efiicient because of the largeamount of air required. Accordingly, the cooling air is frequentlypassed through the layer on the half ofthe support remote from the kilnand the partially-heated air isthen passed through the remainder of thelayer. This double pass method is more economical with respect to theamount of air required than the single pass method, but requires about25% more support area for an equivalent cooling operation.

The present invention is directed to the provision of a method ofcooling hot material issuing from a kiln by the use of cooling air,which requires substantially less air and support area than arevrequired in the single pass'method above described and can be practicedby the use of a support not made of expensive heat-resistant steel.

The new method involves a double pass of the material, in that a layerof partially cooled material is formed upon a support and the hotmaterial issuing from the kiln is deposited on that layer. The bedformed of the two layers is advanced on the support and cooled by a'single pass of air therethrough and, at the end of its travel, the bedis divided into at least two fractions dif-- fering in temperature. Thecool fraction is then discharged, while the warm or partially cooledfractionis returned to the part of the support near the kiln to form thelayer, which becomes the lower part of the bed.v

-The apparatus for the practice of the method comprises a chamber havingan inlet and an outlet and subdivided'into upper and lower sub-chambersby the airpermeable support,.which may .bea. travelinggrate, .but

is preferably a fixed grate with conveying elements reciprocatingthereon. At the end of the support adjacent the outlet, means areprovided for dividing the bed of material and such means preferably takethe form of a blade lying parallel to the the surface of the support andacting to separate the bed into a lower cooled fraction and an upperpartially cooled fraction. The partially cooled fraction is returned tothe support near the chamber inlet to form the layer on the support andis preferably screened to remove both over size lumps and fine particlesbefore being returned. Also, before return of the partially cooledfraction to the support, the fraction may be subjected to a crushingoperation, if it contains oversize lumps in too great a proportion topermit their removal by screening. The lower cooled fraction is carriedout of the chamber and, if desired, may be subjected to a supplementalcooling operation before discharge. Fine particles, which have passedthrough the support, may be collected and combined with the finishedcooled product. The hot cooling air, which has passed through thesupport, travels through a connection to the kiln, Where it serves assecondary combustion air, While a controlled proportion of the heatedair may be removed from the chamber and employed as primary air ofcombustion or discharged into the atmosphere. The hot material issuingfrom the kiln travels through the connection counter-current to theheated air, and is deposited on the layer of material on the support tocomplete the bed to be cooled.

For a better understanding of the invention, reference may be made tothe accompanying drawings, in which- Fig. 1 is a vertical longitudinalsection on the line 1-1 of Fig. 2 of a cooling apparatus embodying theinvention;

Fig. 2 is a sectional view on the line 2-2 of Fig. 1;

Fig. 3 is a sectional view on the line 3-3 of Fig. 2;

Fig. 4 is a front elevational view with parts shown in section of amodified form of the apparatus;

Fig. 5 is a vertical longitudinal sectional view on the line 5-5 of Fig.6 of a modified form of the new cooler;

Fig. 6 is a sectional view on the line 6-6 of Fig. 5;

Fig. 7 is a sectional view on the line 7-7 of Fig. 6; and

Fig. 8 is a vertical sectional view through the discharge end of anothermodified form of the new cooler.

In Fig. 1, the cooler 10 is illustrated as mounted below a hood 11, intowhich the lower end of a rotary kiln 12 projects with the burner tube 13passing through the hood and entering the end of the kiln. The coolerincludes a chamber 14, which has side walls 14a andend walls 14b linedwhere necessary with refractory material, and the top of the chamber isprovided near one end with an inlet opening 15 and a connection 16leading from the opening to the bottom of hood 11. The hot materialissuing from the kiln and discharged into the hood passes through theconnection 16 into the chamber and air, which has been heated by coolingthe damper 19 leads upward through the burners platform The interior ofthe chamber 14 is divided into upper and lower sub-chambers by anair-permeable support, along which a bed of the material travels throughthe chamber. The support may be a traveling grate, but is ml or slightlydownwardly. inclined, in the direction of Patented Mar. 31, 1959travelof thematerial away from the inlet opening 15-,-

and the material is advanced along the support by conveymg elements 21resting on top of the support and connected throughthe support to astructure 22, which 1s-.-mounted beneath the support and is reciprocatedby suitable means. The support 20 extends from the chamber end wall 14badjacent the inlet 15 to a vertical transverse partition wall 23extending between the chamber side walls 14a and cooling air is admittedinto the subchamber beneath the support through a plurality of openings24, to which lead pipes connected to a fan.

The material traveling along the support is in the form of a bed 25 madeup of a layer 26 of partially cooled material, which is distributed uponthe support 20 near the end wall 14b adjacent inlet 15 by a chute 27leading downwardly from the upper end of an elevator 28. The hotmaterial 29 issuing from the kiln and entering the cooler through theconnection 16 is deposited on the top of layer 26 and forms the upperpart of a bed advanced along the support.

Just before the bed 25 reaches the end of support 20, it is subdividedinto upper and lower fractions by a blade 29, which is mounted on theinner ends of a plurality of bars 30 forming a screening device. Theouter ends of the bars are pivoted on a shaft 31, to which is attached ahandle 32 adjustable to diiferent positions along a curved guide 33 andcarrying a counterweight 34. The upper fraction of the bed travels overthe blade 29 and falls between the bars 30 with oversize lumps 35retained on the bars and later removed from time to time throughclean-out doors 36 in the end wall of chamber 14. After passing the bars30, the fraction lands upon an inclined screen 37, which lies betweenand is supported by partition walls 38, 39', which extend across thechamber 14 from one side wall 14a to the other. The material, whichslides off the screen, falls through a passage 40 lying between wall 39and the adjacent end wall14b of the cooler and the material lands on afloor 41, which closes the bottom of the space between walls 38 and 39and the lower end of passage 40. Floor 41 has an opening 41a, throughwhich the material enters the casing of a drag chain conveyor 42, whichextends lengthwise of the cooler and delivers the'material to the lowerend of elevator 28.

The fine material, which falls through the support 20, collects on thefloor 43 of the sub-chamber beneath the support and the material iscontinually removed from the sub-chamber by a pair of screw conveyors44, the forward ends of which lie within cylindrical casings 45surrounding openings in wall 23. The material leaving the conveyorscollects on a floor 46 having openings from which lead inclined chutes47. The fine material, which has passed through-screen 37 and collectson floor 41, flows-through openings 38a in wall 38 and lands upon floor46 to mingle with the material being advanced by the conveyor screws 44.The combined fine material flows through chutes 47 and is deposited upona conveyor 48.

A pair of plates 49 are mounted between the walls 23 and 38 and theplates 49 meet in the median longitudinal plane through the cooler anddiverge downwardly past the edges of floor 46. Near the lower ends ofthe plates, they form parts of chutes 59, which terminate above theconveyor 48. The material, which forms the lowerlayer 26 of the bed andhas passed twice through the cooler,

falls from the end of support 20 and lands upon plates.

49. The material then slides down the plates and through the chute St)to the conveyor 43, where it is mixed with the fines discharged throughchutes 47.

In the operation of the'apparatus, thehot material issuing from the kilnfalls upon alayer ofpartially cooled material covering the support 20.so that the support is protected against damage from the hightemperature of the hot material. During the advance. of the bed ofmaterialalongthe support, the. material .is cooledzby the.

flowof air forced therethrough and the major proportion of the air,which is heated by contact with the material, enters the kiln to serveas secondary air of combustion, while a controlled minor proportion isdrawn olf through stack 18 for use as primary air of combustion or fordischarge to the atmosphere. At the end of the support, the bed of thematerial is divided by the blade 29 and the material, which has made itssecond passage through the cooler, falls upon plates 49 and isdischarged upon conveyor 48 through chutes 50. The partially cooledmaterial traveling over the top of the blade 29 'is first screened bybars 30 to remove oversize lumps and then by screen 37 to remove finesand the screened material is delivered to the conveyor 42 and returnedto the cooler by elevator 28 and chute 27 to form the underlying layeron the support. The fines, which have passed through the support, andthe fines from the fraction being returned, which have passed throughthe screen 37,- are removed from the cooler and discharged upon conveyor48: The cooled material plus the fines is delivered by conveyor 48 to aplace of discharge.

Inthe modified cooler shown in Fig. 4, the drag chain conveyor 42 andits casing and the elevator 28 are dispensed-with. Also, the passage 40receiving material, which slides ofi screen 37, is replaced by ahorizontal casing 51 having an opening 51a, through which the materialsliding off the screen enters the casing. Casing 51 extends acrossthefront of the cooler and encloses a drag chain conveyor 52, whichadvances the material through the casing to a chute 53 leading to thebottom of an elevator 54. The elevator extends upwardly at an anglealongtheside of the cooler to a point adjacent the top of chute 27 andthe chute is connected to receive materialfdischarged by the elevatorand lead the material into the cooler to form the underlying layer onsupport 20. Thus, in the modified construction, the horizontal conveyor51 and the inclined conveyor 54 take the place of the horizontalconveyor 4-2 and the elevator 28.

In' the modified construction shown in Figs. 5-7, incl., thebed 25'being advanced along the permeable support 20- is divided into twofractions by the blade 29' and the lower fraction, which has been cooledby two pas-.- sages through the cooler, enters a chamber 55 defined by.partition walls 56 and 57, which extend across the cooler between itsside walls. The material entering chamber 55 falls upon an inclinedair-permeable support 58? and air under pressure is admitted to thechamber beneath the support through an opening 59 connected by a pipe 60to a fan. The air travels through the support and the layer of materialthereon and is discharged to the atmosphere through an opening 61, fromwhich a pipe 62 leads to a stack 63 containing damper 64. The materialsliding from support 58 lands upon a floor 65' having an opening 65a,through which the material travels to fall upon fioor'43. The wall 56 ofchamber 55 has a pair of openings surrounded by cylindrical casings 45',into which extend the ends of conveyor screws 44"operating in thesub-chamber beneath the support 20' to discharge the fine material whichhas passed into the sub-chamber through the support. The fine materialcombines with that issuing from chamber 55 through the opening 650 andthe combined material leaves the cooler through a pair of chutes 47discharging into a conveyor 48'. The material, which passes over theblade 29, is screened for removal of. oversize lumps by:'bars 30 andthen falls upon a screen 37'. The fines passing'through screen 37 fallupon a floor plate- 66 having an opening 66a, which permits the materialto fallzup'onifloor 43'. to escape. through chutes 47. The" mounted on ashaft 67 supported in the side walls of the cooler and having anoperating handle 68 at one end for adjustment of the blade in relationto the support 20'. The bars 30 forming the grate for removal ofoversize material are not attached to blade 29' or to shaft 67 but arefixed in position and not adjustable with the blade.

With the construction shown in Figs. 5-7, incl., the quantity of airemployed for cooling the bed 25' is controlled, so that it provides theamount of air, which can be utilized in the kiln as secondary air ofcombustion. The cooled fraction of material leaving the bed is thengiven its final cooling in chamber 55 by air supplied through pipe 60.The air used in the supplemental cooling of the fraction is controlledin amount by the damper 64 and is discharged into the atmosphere. Withthe arrangement described, no excess air is introduced into the kiln andthe amount of air employed in the supplemental cooling of the materialis controlled to give the desired cooling effect without waste.

The modified construction shown in Fig. 8 is the same as that shown inFigs. 5-7, incl., except that the means for conveying the bed 25' ofmaterial through the cooler takes the form of an endless chain grate 69of conventional form and mounted on sprocket wheels 70 on transverseshafts 71, one of which is driven. Because of the differences betweensuch a traveling chain grate and the conveying means used in the otherconstructions shown and including the stationary support 20', the wall56' of the supplemental cooling chamber 55' in the Fig. 8 constructionhas been changed from that shown in Figs. 5-7, incl., to provide roomfor the returning stretch of grate 69. The operation of the Fig. 8cooler is the same as that of the cooler shown in Figs. 5-7, incl.

I claim:

1. A method of cooling hot granular or lumpy material issuing from akiln, which comprises continuously forming a substantially uninterruptedlayer of partially cooled material and advancing the layer in its plane,distributing hot material issuing from the kiln upon the layer adjacentthe place of formation thereof to form therewith a traveling bed,passing cooling air upwardly through the bed to cool the materialtherein, dividing the bed at the end of a selected travel thereof intoat least two fractions differing in temperature, discharging the coolestfraction, and returning another fraction of the bed to the place offormation of the layer and utilizing the returned material for theformation of the layer.

2. The method of claim 1, in which a controlled proportion of the air,which has passed through the bed, is directed to the kiln for use in thecombustion of fuel therein.

3. The method of claim 1, in which the bed is divided into cooled andpartially cooled fractions and air is passed through the cooled fractionafter separation of the fraction from the bed.

4. The method of claim 3, in which the amount of air passed through thebed is controlled so as to be not substantially in excess of thatrequired as secondary air of combustion in the kiln, and air is passedthrough the cooled fraction after separation of the fraction from thebed to cool the fraction to the desired final temperature,

the air passed through the fraction being discharged into theatmosphere.

5. The methodof claim 1, in which fine particles fall from the layer andare combined and discharged with the coolest fraction of the bed.

6. The method of claim 1, in which the bed is divided into upper andlower fractions, of which the lower fraction is formed of the layer andthe upper fraction is formed of the material which was deposited uponthe layer, the lower fraction is discharged, and the upper fraction isutilized in the formation of the layer.

7. The method of claim 6, in which the upper fraction removed from thebed is screened to remove oversize lumps before being utilized for theformation of the layer.

8. An apparatus for cooling hot granular or lumpy material issuing froma kiln, which comprises a chamber having an inlet at one end and anoutlet spaced from the inlet, means for supporting a bed of materialwithin the chamber and advancing the bed from the inlet to the outlet,including an air-permeable support extending from beneath the inlettoward the outlet and dividing the interior of the chamber into upperand lower subchambers, means for supplying air to the lower subchamberfor passage through the support and bed into the upper sub-chamber,means adjacent the inlet for distributing partially cooled material uponthe support to form a layer, means adjacent the outlet for dividing thebed into at least two fractions differing in temperature, means forconducting a cool fraction of the bed to the outlet, means fortransferring a warm fraction of the bed to the distributing means, andmeans for conducting heated air from the upper sub-chamber through theinlet to the kiln and hot material from the kiln through the inlet to bedeposited upon the layer on the support.

9. The apparatus of claim 8, in which the bed is divided by a bladeextending across and parallel to the surface of the support and enteringthe bed of material.

10. The apparatus of claim 9, in which the blade is movably mounted foradjustment to vary the spacing of the edge of the blade from thesupport.

11. The apparatus of claim 9, in which the fraction passing over the topof the blade falls upon a screening device for retaining oversize lumps,while allowing the remainder of the fraction to pass.

12. The apparatus of claim 11, in which the fraction freed of oversizelumps travels over a screen, through which fine particles pass forcombination with the cool fraction to be discharged.

13. The apparatus of claim 9, in which the fraction passing beneath theblade enters a compartment and falls upon an air-permeable support, andmeans are provided for passing air through the material on the supportin the compartment and then discharging the air into the atmosphere.

14. The apparatus of claim 8, in which means are provided for removingfrom the lower sub-chamber ma terial, which has entered the sub-chamberthrough the support.

References Cited in the file of this patent UNITED STATES PATENTS

